NON-HEAT TREATED ROLLED STEEL AND DRAWN WIRE ROD WITH EXCELLENT TOUGHNESS, AND METHOD FOR MANUFACTURING THE SAME

摘要

There is provided a rolled steel with excellent toughness, a drawn wire rod prepared by drawing the rolled steel, and a method for manufacturing the same, in which even if a heating step is omitted, the toughness of the steel can be improved by securing a de-generated pearlite structure in an internal structure of the rolled steel by controlling a content of Mn among components and cooling conditions, and then preventing C diffusion. The rolled steel according to the present invention includes C: 0.15~0.30 %, Si: 0.1~0.2 %, Mn: 1.8~3.0 %, P: 0.035 % or less, S: 0.040 % or less, the remainder Fe, and other inevitable impurities, as a percentage of weight, in which the microstructure of the rolled steel is composed of ferrite and pearlite including cementite with 150 nm or less of thickness.